Automatic telephone system.



E. BLOS.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED DEC. 21, 1909.

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E. BLOS. AUTOMATIC TELEPHONE SYSTEM.

APPLICATION r1221: DEO.21, 1909.

Patented Dec. 10, 1912.

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E. BLOS. AUTOMATIC TELEPHONE SYSTEM. APPLICATION TILED DEG.21, 1909.

1,046,952. Patented Dec. 10, 1912.

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APPLIGATION FILED DEG.21, 1909.

Patented Dec. 10, 1912.

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AUTOMATIC TELEPHONE SYSTEM.

APPLIGATION FILED D130. 21, 1909.

Patented Dec. 10, 1912.-

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AUTOMATIG TELEPHONE SYSTEM.

APPLICATION FILED DBO. 21, 1909.

1 46,952, Patented Dec. 10, 1912.

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,5 ll i x I I I I I I I I ERNST BLOS, OF SCHijNEBERG, NEAR BERLIN,GERMANY.

AUTOMATIC TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Dec. 10, 1912.

Application filed December 21, 1909. Serial No. 534,267.

To all whom it may concern:

Be it known that I, ERNST BLos, a citizen of the German Empire, andresident of 10 Konigsweg, Schiineberg, near Berlin, Germany, haveinvented certain new and useful Improvements in Automatic TelephoneSystems, of which the following is a specification.

The main advantages, as compared with existing systems, of the newsystem of aut0- matic telephony herinafter described, are first, thatthe number of current impulses necessary for making the connectiondesired is reduced to two per digit of the subscribers number; secondly,that only such of the contacts which are used to make the one individualconnection, are subjected to Wear, and thirdly that the only movementofthe selectors is a linear one over a maximum distance of one or twomillimeters. None of the rotary or stepping movements which characterizethe selectors of former systems are employed. In the well known Strowgersystem, the number of current impulses per digit reaches ten; themovement of the contact arms of the selectors is a stepping one overintermediate contacts which latter are not only useless for making thedesired connection but are also subjected to useless. wear at each ofthe connections made. A further advantage of the selectors of the newsystem is that they can be actu ated directly by the line current, andthat the adjustment of the preliminary selector which connects thecalling subscriber to one of the first selectors which is not engaged iseffected at one single stroke, and in the same manner the adjustment ofeach of the following selectors is effected. Therefore all connectionsare made within a very short time and in a very simple manner. Each ofthese advantages is obtained by the fact that the principle of selectingis not a quantitative one, as in the Strowger system, but a qualitativeone, e. thedigits are not transmitted by means of a chosen number ofcurrent impulses of the same kind, but by a combination of impulses ofdifferent kinds, the number of impulses being the same in each case. Thedifferent character of the current impulses which are applicable to mysystem can be attained by varying their direction, or their intensity,or their frequency (in the case of currents of alternatiug orintermittent currents). or by sending impulses of the same characterover difi'erl ent lines. A series of three difierent kinds of currentimpulses can be obtained for example by earthing a double lineconsisting of two-line wires L and L (1) earthing the line L, and notearthing L or (2) earthing the line L and not earthing L,,, or (3)earthing the lines L, and L, simultaneously. This isthe method ofproducing three difl erent current impulses which wil be used in thefollowing description of my improved'automatic exchange system. Thenumber of different current impulses available being three, it isnecessary to use two-impulses of such kind so as to transmit each digit.In this way I obtain a total number of nine different combinations ofimpulses. This is suflicient for transmitting nine of the ten digits ofthe decimal scale; when numbering the subscribers therefore, one of theten digits must be dispensed with, for instance, the Zero. and all ofthe numbers containing the cipher 0 must also be omitted.

The improved automatic selectors consist substantially of a series oftoothed disks which. by means of small electromagnets, are moved througha very small angle, and around Which disks a series of flat tongues,parallel to the axis of the disks. are arranged. If pressed against thedisks, only one of these tongues, corresponding to the relative positionof the disks, can fall into ,the grooves of the disks and close thedesired circuit.

I shall first generally describe the principle of selecting which Iemploy and then proceed to describe the arrangement of an exchange for 9subscribers. The selectors of this exchange are divided. as usual, intothe three general classes viz. (1) preliminary selectors, (2) firstselectors. and (3) second or final selectors. The preliminary selectorsconnect the calling subscriber to a first selector which is not.engaged; the first selectors select the hundreds; and the secondselectors select the tens and units of the called subscriber. Thearrangement of the preliminary selectors is novel in that they areconnected to the subscribers by means of single wires, the number of theselectors nevertheless being not greater than in the improved Strowgersystem. Beside the so lcctors mentioned there is a further singleselector interconnected between the first and second selectors. Thissingle selector which is called a central selector, transmits thecombination of current impulses corresponding to the nearest free secondselector within the calling hundreds to the calling first selector.

The principle of selecting employed will be understood from Figures 1 to5, Figs. 1 to 3 whereof relate to the manner of transmitting digits andFigs. 4 and 5 to the manner of selecting a disengaged first or secondselector. Figs. 6 and 7 show the arrangement of the combinations and theteeth on the selector disks. Figs. 8 and 9 show the construction of oneof the first and second selectors, Fig. 8 is a section on the line XX ofFig. 9, Figs. 10 and 11 that of the central selector, and Figs. 12 and13 some details of the preliminary selectors.

Figs. 14 to 18 are diagrams of the connections for an exchange having 9:729 subscribers.

The principle of scZecting.If a number (say 2) of different signs isavailable, and 1 each variation is composed of n terms, the wholepossible number of variations is 2. For instance, we can form, by meansof the signs 0 and m, if each variation is to be composed of two terms,the following four variations:

(1) o o (2) o w w u (4) a: m

Now let us imagine two line wires, L and L in each of which may existone of the current conditions. (1) o no current flowing through the linewire. 2) Q3 21 current of any kind flowing through the line wire. Then-Variation l no-current in both line wires.

2::current in line I. only.

3:0urrent in line 1J3. only.

4mnent in both line wires.

1. 0 w o a; 2. o a: a: 0 3. 0 w w a; 4. m o o m 5. a: o w 0 6. a: 0 m a:7. w w o a: 8. w m w 0 9. w m m m La b L1 L1.

Each of these 9 variations consists of 4 terms, and is also to betransmitted over the two lines L and L,,. This is done, for

example, in the case of the variation 1 by sending two successivecurrent. impulses through the line L in the case of variation (3 byfirst sending an impluse through L and then an impulse simultaneouslythrough both L and L,,. In the case of variation 9 it would be etlectedby first sending an imjulse simultaneously through both L and L and thenrepeating this operation. An example showing practical application ofthis principle is shown in Figs. 2 and 3. Fig. 2 illustrates four bars(1) each of which is provided with 9 grooves (2 and 3) and correspondsto one of the four vertical columns of Fig.

1. Across the bars nine tongues (No. 19), are arranged. The grooves ofthe bars may take up two possible positions relatively to the tongues1-9. The grooves 2 are arranged precisely below the tongues, but the g5grooves 3 are displaced upward by a distance :0 from the center of thetongues. The arrangement of these grooves is arrived at by substitutingfor 0 in Fig. 1 a groove which lies below the tongue, and for m a groovewhich lies at a distance a: from the tongue. Considering now the tongue1, it may be caused to fall into the grooves on the parallel bars bydisplacing the bars II and IV downward through a distance a:

from the position illustrated. By this displacement of the bars all theother 8 tongues are prevented from falling in: the tongues 2 and 3 bythe bar III and the tongues 4 to 9 by bar I; In this way each tonguecorresponds to a certain combination of the bars displaced, and in allcases only that tongue, and none of the others, n fall in, whosepredetermined combination is produced.

From this it is clear that by displacing one or more of the bars, aproper and accurate selection of any of the tongues may be effected.Fig. 3 is a diagram of connections of the electrical circuit forselecting the tongues over the two lines L and L The current flow stateof the wires L and L is in this example effected by earthing the line ofthe battery B. Magnets 1a,, m m and )ILW are arranged in the batteryline behind the arm of a switch in such a manner that the magnets m andm are connected to the lines L and L and after the first current impulsehas been passed over the line, the magnets m and m are connected to thelines L and L,. The progressive movement of the ratchet mechanism iseffected by the magnet m which is energized each time either or both ofthe lines L and L is or are earthed. The magnets m to m operate the IVrespectively. For selecting the tongue 1 for instance, a movable earthedcontact is moved over the row 1 in Fig. 3. When the contacts of this roware earthed by the movable earthed contact the magnet m is ener- 13adiagrammatically the 75 slotted bars F to tyt gized over the line L andthereby the bar II is moved through the distance .7. In addition themagnet m energized and the arm of the ratchet is moved right over theterminals ot' the magnets III and IV. \Vhen now the lower contact of therow 1 in Fig. 3 is carthed through the moving contact, the mag et m isenergized and the bar 1 of Fg. 2 moved downward through the distao (1that the tongue 1 now falls into the grooves of the parallel bars.Simultan'eously the magnet 11/ is energized and the arm of the step-hystcp switch is moved 'hrouglt another step. It will he understood fromthe foregoing description that only the tongue 1 falls into the groovesof the bars. It is of course neces ary that the bars be retained in thepositions to which they have been moved by the magnets. The meansproposed for etfecting this will be described later as tll 0 shall themeans used for re urning the step-by-step switch arm into its initialposition.

In Fig. 1 the arrangement of the grooves or teeth on the bars issubstantially the same as in Fig. 2-the edges of the bars pressedagainst the tongues being inclined in order to obtain automatic returnof the bars. This arrmigement is applied at the central selcctor andwill he specially described when describing the central stationarrangement.

The variations according to Fig. 1 may be transmitted simultaneouslyinstead of in two parts over two wires it' 4 wires L,, L L L as shown inFi 5 are provided. Each wire is then connected to one of the fourmagnets m, to m and the step-by-step mechanism is entirely dispensedwith. For example to select tongue No. b, the threefold switch No. (3 ispressed downward whereby the lines L L L, are carthed, the magnets mmand m cncrgized and the rods I, III and IV moved. As can be seen fromFig. 2. only the tongue 6 can fall into the grooves of the bars. Thismomentary transmission of the 9 variations of current is employed on theprel 'ninary, first and auxiliary selectors. In the case of thepreliminary selector however the variations 0 0. 0 0 must he providedand therefore the four bars must he provided with holes or groovesarranged directly under or opposite a tenth tongue. This tenth tonguewill of course be normally in the grooves and as soon as one or other ofthe bars is moved the tenth tongue will he raised out. of the groovesand suitable contacts are thereby operated.

The table of comltina ions or 'ariations given in Fig. 6 is derived fromthat given in Fig. 1. by writing each of the variations in that figurenine times to form 9 groupsthereby forming the rows I to IV. in Fig. 6.The rows V to VIII are formed by using th 9 variations of Fig 1successively in each group in Fig. 6. The toothed or grooved bars, seeFig. 7, and the corresponding tongues are disposed relatively to oneanother in the manner corresponding to the table in Fig. 6 and asexplained with reference to Fig. 2. In the position of eaclro there is agroove under the tongue and in place of each a the groove is at adistance a from the tongue. In order to simplify the arrangement of thegrooves the distance a: is made equal, in Fig. 7, to half the pitch ofthe tongues. Further, for reasons hereinafter explained, the spacebetween each group of nine is greater than the pitch of the tongues ineach group. To test the correctness of this arrangement let us followthe selection of the tongue 99. According to the table in Fig. 6, allthe bars have to be moved in order to allow the tongue to fall into thegrooves-see Fig. 7at the foot. ()11 the other hand all the other tonguesmust remain out of their grooves. The tongues 11-39 are held out by thebar I, 4169 by bar II, 71-79 by the bar III, 81-89 by the bar IV, 91-93by the bar V, 94-96 by the bar VI, 97 by the bar VII and 98 by the barVIII.

I shall now proceed to describe a selector which may be taken asrepresentative of all the selectors which are required, with theexception of the central and preliminary selectors. In Figs. 8 and 9 asecond selector is illustrated by way of example, Fig. 8 being anelevation and Fig. 9 a plan. In the first place, imagine the teeth andgrooves of Fig. 7 as arranged on the peripheries of disks, which may berotated through a small angle equal to half the pitch of the tongues. InFig. 8 there are eight disks 4 which are loosely rotatable on disks 5and these latter disks are arranged side by side, on a member 6 andpressed together by a closing disk 7. The disks 4 are controlled bymagnets 7m, m m to m which are all fixed to a plate 8. The magnet m forexample, controls the bottom disk 4 in Fig. 8 by means of its rightangled armature 9 which engages in a. groove on the disk. In order toretain the disk in its position of rest or working position, as the casemay be. a flat. spring 11 is arranged for each disk and is mounted on apin 10. The flat springs 11 are adapted to engage in one or other of twonotches on the'disks, corresponding respectively to the position of restand the working position. The magnet m serves to return the disks intotheir position of rest. its bell-crank armature 9* engaging in a notchin every one of the disks 4, as seen in Fig. 8. The tongues 12,supported opposite the grooves on the peripheries of the disks are heldwith their ends working in grooves on the bed plate of a magnet M, andare all pressed against the disks 4 when the magnet M is energized. Eachtongue is pro vided at its upper end with a part 13, which carries thecontacts 14 and presses them,

when the tongue drops into the grooves on the disks, against the contactring 16 which is cast in the insulating ring 15. The insulating ring 15is itself fixed to a plate 17 which is fastcwd to the supporting body 6for the disks. The contacts 11 are also cast into an insulating ring 11which is fastened to the bed plate of the magnet M.

As mentioned above, the second selector just described is also typicalfor first selec tors. The central selector is constructed somewhatdifferently and will be understood from the following description ofFigs. 10 and 11. The preliminary selector is constructed somewhatsimilarly to the central selector but has some modifications which are,illustrated in ligs. 12 and 13. In the central selector it is necessarythat the tongue to be selected fallssimultaneously with the motion ofthe bar 18 and that it has closed its electric circuit at the time whenthe bar completes its motion. To this end'the tongues 19 are, under theaction of springs 20 (Fig. 11) continually pressed against the bars 18.The bars 18 are longitudinally slidablc in guides 21. The sliding motionof the bars is produced by ma gnets m -m and when these becomedeenergized the bars 18 are returned to their positions of rest bysprings 22. In order to facilitate as much as possible, the returnmovement of the bars, the teeth on which the tongues bear in theposition of rest are inclined with a slow inclination as described abovewith reference to Fig. 4. In the case of a preliminary selector, it isnot necessary that the bars be immediately returned but the bars mustremain in the position to which they have been moved, until thesubscriber returns the preliminary selector back to the disengagcdposition at the end of the conversation. Each bar is therefore held inits drawn out position by means of a pawl 23 (Figs. 12 and 13) whichengages in a special groove 24 on the bar. This pawl remains inengagement until all the pawls in engagement are withdrawn by means of aright angled armature 25 on the magnet M (Figs. 12 and 13).

The principle of selection employed has now been described withreferenceto Figs. 1 to? and suitable selectors for the various purposes have alsobeen briefly described. I shall now proceed to describe the arrangementof a station having 9 (i. e. 729) subscribers.

Exchange for 9 subscribers. At this statici only the digits 1 to 9 areemployed for nun' rering the subscribers -the cipher 0 must be omittedfor the reasons given at the beginning of this specification. Furtheronly numbers each comprising 3 digits are employed. The numerationtherefore commences with 111 so that it is unnecessary to precede unitsor tens with a corresponding number of naughts as is necessary in othersystems.

The subscribers are numbered--111119, 121-129 and so on to 191-199;211219, 221 229. and so on to 291299; 311l9, 321329 and so on to239L399. and so on until 911- 919. to 991%)99 all numbers between 111and 999 and containing the cipher 0 being omitted. -\s in other systems.the subscribers are divided into groups but whereas each group in othersystems embraces 100 I divide them into groups of 81. so that in thepresent instance there are 9 groups. The first group embraces thenumbers 111499; the second group the numbers 211299 and so on till theninth group embraces the numbers 911999. For each group of subscribersthere must be provided as many first and second selectors as the maximum11- mated number of simultaneous conversations. In the present instance9 simultaneous conversations are estimated and provided for in eachgroup which is about 11 per cent. and usually sutlices. Each group ofsubscribers are given nine first selectors which are made available toeach subscriber by a ninefold contact on the preliminary selector. Inaddition to the nine-fold contact av tenth is provided for eachsubscriber, as above mentioned, to act as a switch. Each subscriber ispermanently connected to this switch and is automatically connected bylifting his receiver to one of the nine first'sclectors over thenine-fold contact. As usual a preliminary selector is provided for eachsubscriber, which preliminary selector is provided with the nine-foldcontact and the return contact.

In Fig. 14 there is illustrated a preliminary selector to which it shallbe assumed that subscriber No. 124 is connected. The multiple ormanifold contactsf to f are connected to the trunk lines a, I), 0 to a.b 0,. These trunk lines have branch connections to all the nine-foldcontacts of the 81 preliminary selectors for one group of subscribers,only the zero or naught contacts being omitted-for example f is omitted.From the trunk lines (L -(5., and Z ,b.. lines branch off to nine firstselectors, the first of which is illustrated diagrammatically in Fig.16. The lines 0, to c, are connected to the relays 13-11 of Fig. 15which are all connected to the positive pole of the battery B. Theserelays close a set of contacts arranged in series and from which fourlines lead over the switch a, to the four magnets m to m In the positionof rest the contacts from r, connect up all four magnets m; to 111-w tothe negative battery pole over the lines 26, 27 and 28. In the workingpositions these contacts connect the magnets m m to the contacts from 1'These last mentioned contacts when in their position of rest connect themagnets m m and m to the negative pole B, and when in their workingposition they connect the lines leading to all four magnets to thecontacts of 1 and so on in the same way throughout the group, thecontacts of each relay in turn close the magnet circuits, when in theirposition of rest, in the same order as the letters as in the table ofvariations given in Fig. 1. In the working position the contacts of anyone relay always con nect up the contacts of the next following relay tothe lines leading to the magnets. The lines leading to the switch 8 alsobranch ott' to the switches of the other 80 preliminary selectors of thesame group of subscribers so that the magnets m to mv of the subscriberin question are connected to the contacts of the relay 23, the switch 8,of which will be just closcd'by the relay r of the calling subscriber.As this closure of the circuits is only a momentary one, it ispractically impossible that the switch 8 be l closed simultaneously bytwo selectors and that thereby two subscribers are connected to the samefirst selector. Care must now be taken that r, is immediately switchedover on to the contacts of 1, after magnets m to m are energized. Thistakes place, as described later, as soon as that tongue at thepreliminary selector which corresponds to the first selector selected,falls into the grooves in the bars. The double line leads from thesubscriber's station to two current rails'a and b A third rail isconnected over the magnet winding of m and the line 28 to the negativepole of B. The lines a and Z), form the speaking circuit and the line cforms the blocking circuit. The lines a and 6, are also connected to thecontacts 29 and 30 against which springs 31 and 32 rest. From these thelines a and 5 lead to the second selector which has the connections Nos.111-199. A branch from the line 6 leads past the spring 32 to the relay1' which is also connected over the line 33 to the positive pole +13.The negative pole of B is earthed. \Vhen therefore the subscriberpresses down the key 12 i on the right the following current impulse istransmitted: positive ole of B, 33, r spring 32, contact 30, righthand124 key of the station, earthed to negative pole of battery. The relay rcloses switch 8 If now all the first selectors of the callingsubscribers group are disengaged, that is to say the relays r, to 1',are not excited, then current passes from the positive pole of B andline 26 only over the contacts which are at rest, the s rings of therelay r magnets m,m v and ines 27 and 28 to the negative pole of Thefour magnets move their corresponding bars so that, according to Fig. 4,the tongue No. 9 can fall into its grooves.

J In this way both lines of subscriber No. 124 are connected to thelines of the first selector (Fig. 16) over the lines a and b the twoupper springs f and the trunks .a and 1),. Since the under spring fbears I on the line c the following circuit will be closed :-+B, 26, 1'0 under spring f c m 28 and -I. The relay 1', is vthereby energized andits springs switch over the lines for s, to the contact springs r Inthis way the first selector of the subscribers group is in the engagedposition and the next calling subscriber from the same group will beconnected up through the contacts of r to the second first sef lector.In the circuit of the relay 1*, there i is also arranged the magnet m whch has to be cut out by the contacts of the prelimii nary selector atthe end of the conversation. f It must therefore be so dimensioned thatit I reu ains inoperative when in series with '13. It is renderedoperative as described later bv short circuiting 1' The purpose of thecontacts 29, 30 and 34 remains yet to be explained. While the contacts29 and 30 break circuit when the bars are moved, the contact 34 makescircuit. I The former, 29 and 30, prevent the calling I subscriber frombeing called up and and the current impulses now about to be transmittedhave no more influence on the pre liminary selector. The latter, 34,closes the l blocking line c over 35, 34, 27, 28 to the negative batterypole and the subscriber ht is engaged for all other calling subscribers.The action of this connection will be explained more fully later. Thecalling 'subscriber is therefore connected momentarily to the firstselector Fig. 16 by once carthiug his 0 line and may now get on to thedesired number by 6 further current iml pulses. Assume now that No. 124wishes to call up No. 419. He must first pass his earthed contact overthe row 4 in Fig. 3 whereby two current impulses are trans-- mittcd tothe first selector. The first impulse is over line L, and energizes M,the second over line L, and energizes M. IV of the first selector. Theswitching over is effected by ratchet mechanism, the arm of which restson the contacts 36 and 3 7 in the pcsition of rest of the selector. Thisratchet mechanism consists of a disk 100, partially toothed, havin twoprojecting parts 101 and 102 and being held under pressure by a spring103. The disk is held in position by a ratchet 104 which fits into theteeth of the disk and which can be attracted by the magnet m being itsarmature. The hook 105.

which is linked to the armature 41 of the forwarding magnet m is alsopressed against the toothed circumference of the disk by means of thespring 106. When the armature 41 is attracted by the magnet m itslinkedhook 105 gets into the next higher tooth, pawl 104 meanwhile securingthe position of the disk. If, now, m is demagnetized, its armature 41 isreturned by the spring 107, whereby the disk is turned and thecontactpieces of the arm 101 reach the contacts 42, 43 and 44. The sameaction is repeated on occurring of the next current impulse energizing mafter which the arm 101 covers the contacts 58 and 59. The arm isrestored into its rest position by energizing the magnet m the latterattracting its pawl-armature 104 and thereby simultanemisly retractingboth pawl 104 and hook 105 irom the teeth of the disk, whereby the diskis allowed to follow the traction of the spring 103.

The full circuits are as follows: (1) L earthed; B, line 38, m 39, m (1upper spring f a left hand key 124 l, earth to negative pole of B. Therotation of one of the disks through a small angle is effected by 912 asalso is the closing of can... at). The magnet m; attracts its armature41 and thereby moves the switch arm 36 to the contacts 42, 43, 44. (2)L, is earthed, +B, 38, m 39, m 43 switch arm 37, by, 1),, center springf b right hand key 124 of the station, then earthed to negative pole ofB.

he magnet m rotates its disk and closes its contact 45 which remainsclosed like Contact 40, because the armatures of the operating magnetsremain in their attracted position during the entire duration of theconversation. The attraction of the armature 41 by we; also closes thefollowing circuit: +13, 38, 46, 47, 48, 44, T1,, 49, 50, and thenegative pole of 13. h r,,, consequently closes an 8 pole switch to theleft of r in Fig. 16. In this way the magnet m and the magnet m of thecentral selector (Fig. 17) are energized by the closure of the following circuit :-+B, 51, on the one hand m (Fig. 17) 52, 53 and 40 onthe other hand m (Fig. 17) 54, 55, 45 and then together over 49, 50 tothe negative pole of the tery B. Both current impulses of the digit 4are therefore transmitted to the central selector. The magnets m and mof this selector move their bars whereby the multiple contacts Z,descend and if none'of the second selectors of the fourth hundred areengaged, the combination of the first second selector will betransmitted over the contacts 1;, at the left hand side of Fig. 17 to thmagnets m and m of the first selector (Fig. 16). In detail the principleand working of the groups of relays 1' to 1' is precisely the same as inthe group of relays 1", to r, of Fig. 15. The circuit for this is asfollows :l-B, 56, 57, contact springs of 1" multiple contacts 2,, m andm 49, 59 to B. It is assumed here that the impulse which energizes 7'lasts somewhat longer than the time required for shifting the bars ofthe central se' ct r.

for the magnets WWII and m This may be effected at the sending stationby a suitable arrangement. \Vhen the earthing of the line Lb (Fig. 14)ceases the armature 41 (Fig. 16) moves the switch arm farther on to thecontacts 58 and 59. In this position the exciting circuit of the mainmagnet M of the first selector by means of the metal piece 60 of theswitch arm is closed over 38, 58, 59 and 50 and thereby all of thetongues of the selector are attracted but only the tongue 41 is drawninto the grooves of the bars and the multiple contact 9 at the toplefthand of Fig. 16 pressed against the contact rails 0 b and In thiswaythe subscriber is connected to the switching mechanism of the secondselector (Fig. 18) over the upper springs 9 lines ag and by As the thirdspring g rests on the rails cg, the relay 1' is also energized overlines 56, cg bottom spring g cg, 61 and through the winding of 1, Therelay 1", when in series with 7",, remains inoperative. The relay 1' byswitching its spring, will cause the next caller for a number in thefourth hundred to be switched on at the calling first selector to theNo. 2 second selector of the four hundred group.

The transmission of the digits 1 and 9 is effected by passing theearthed contact over the rows 1 and 9 (Fig. 3) successively whereby L istwice earthed and then L and L together are earthed. In the firstearthing of L current passes from +B over 62, 1a,, 63, m 64, by centercontact arm 9 bg, center contact arm f b L right hand key 124, thenearthed to -B and causes the movement of the disk corresponding to m andalso the movement of the switch arm in Fig. 18 to the contacts 65 and66. This is repeated for the magnet m whereupon the arm covers thecontacts 67 and 68. The earthing of the lines L and L now follows forthe selection of the digit 9. The earthing of the latter follows thecircuit path just described but passes over the magnet m and contact 68.The earthing of L takes place over m 67, ag upper contact arm 9 ag,upper spring f a left hand key 1241 to the earth and The earthing ofthese two lines therefore effects the movement of the disks correscoding to magnets m and m an the switch arm is moved forward to coverthe contacts 69 and 70. The same is repeated After completion of thislatter earthing the switch arm of Fig. 18 has moved into its endposition and closes in the first place the circuit for M, by means ofthe contact piece 71 over 62, 7 2,73, 74. Further in this end positionthe lines cg and by are connected up to the central battery B over 75,76, 77, 78. From the central battery B there lead lines 79 and 80 to therails a and b so that the speaking circuit to the subscriber iscompleted through (1 and b the two upper springs Z lines a and Z1contacts 81 and 82,'and rails a and b The blocking line c of thesubscriber is arranged over the lower contact arm l of the secondselector rail 0,, switch, contact 83, line 74 to the negative pole B.

The relays 1' and r (see below and above the central battery Fig. 18)operate the sounding device 84. As long as the re ceiver of the callingsubscriber remains on its hook and the alarm is in the line circuit, thecalling relay 7",, does not operate. Only when the receiver is liftedand the microphone is switched incircuitin place of the alarm does therelay v3 attract its armature. This relay then closes its contact 85whereby a calling current is transmitted over this closed contact andthe stationary contact of 1' to the line of the called subscriber. Inthis way the called subscribers alarm is operated. At the same time thecalling subscriber hears a humming sound in his receiver which stops assoon as the called subscriber takes his receiver from the book as therelay 7' then attracts its armature and cuts out the sounder. Thismethod of switching in the calling current is however not new.

\Vhen the conversation is ended, the operated selectors must be returnedinto their positions of rest. This is effected by the calling subscriberearthing his line L... Since this line is still connected to 77 overcontact 75, the relay 1* is energized when the line L is earthed. Byclosing the contact 86 of the relay 73 the magnet m is also energizedand this magnet releases the switch arm so that it returns into itsinitial posit-ion and thereby M is cut out. In consequence of the energystored in the arm due to its motion the arm passes over its position ofrest and causes contact for a brief period between the spring arms 87and 88 whereby the magnet m", returns the disks of the second selectorto their starting position. The relay 1",, also closes the contact 89and thereby short circuits the relay r (Fig. 17) of the centralselector, as this relay is on one hand connected through 56 to thepositive pole of B and on the other hand to the branching'point 90,which is further connected directly to +B through line 91 and contact89. This short circuit does not only denergize the relay 1",, andthereby cause its contacts to resume their positions of rest and bringthe second selector into disengaged position but also energizes therelay T of the first selector (see the lowest part of Fig. 16) directover contact 89 from 1",, ofthe second selector, line 91 Cg and Cg andthereby closes both the contacts of this relay. The result of this is inthe first place the energization of m over line '92, contact 93 and line50 whereby the switch of the first selector is released and consequentlyMg de e'ne-rgized. The switch arm of the first selector closes thecontact 94 in the same way as described with reference to the sec- 0ndselector, and thereby energizes 'the re turn magnet m which brings thedisks hack into their position of rest. As in the case of the secondselector, the contact 94 is only closed momentarily, owing to the hinetic energy of the switch arm on returning carrying it past its positionof rest and after this closure of the contact 94 the switch arm setsback into its proper position of rest over the contacts 36 and 37. Thecontact 95 is also closed by the relay 1 whereby r, F ig. 15) is shortcircuited. 1', is connected by means of line 26 between the positivepole of the battery and the branching point 96 which is now connecteddirectly to +B over contact 95 and line 92. By this short circuit therelay 1', is deenergized, its contacts return to their positions of restand the first selector is thereby brought into the disengaged position.The short circuit further causes m of the preliminary selector toattract its armature and the multiple contacts f and f, to breakcircuit. The path of the current is as follows: +B, line 92, contact 95,96, 0,, bottom arm of f 0 m line 28 -13. \Vith this return of themultiple springs f and f the selectors required for the conversation areall returned to their disengaged positions and are ready to be used fora new call.

\Ve have still to consider the case in which the called subscriber isengaged, having been called up, let us assume, by another party. In thiscase the multiple cont-acts No. 1 (Fig. 18) on another second selectorfor the numbers 411 199 already rest on the contact rails a 7),, and cof this other selector and its ratchet mechanism is in its end positioncorresponding to the contacts 75, 76 and 83 of Fig. 18. Its rail 0, istherefore connected through the switch arm to B (in Fig. 18 throughcontact 83 and line 74). Of course all the multiple contacts bearingsimilar numbers are connected in multiple. When now, the switch arm ofthe selector operated by our call, passes into the end position on theoccurrence of the four current impulses which correspond to the digit9,it touches, in passing, the contact 97 By means of this contact, shouldthe called subscriber be engaged, the following circuit is closed: +B,1* line 77,. contact 97, contact arm, rail 0 bottom arm of Z the samearm on the second selector over which the subscriber is already called,the rail 0, of this selector switch arm, contact 83, line 74 to .B. Thiscurrent impulse energizes 7' whereby all the selectors called intoaction by our calling up the engaged subscriber are returned to rest inexactly the same way as when the line was earthed by the callingsubscriber at the end. ofthe conversation. If the called subscriber 419is himself lling up sonie othersubscriber the M118 i r im n nt: lectorarebroken'a l contact 98 is closed, I connected to (exactly as describedcontact and lines hent-herefore the switch arm a 191 uefou w V i n19,194) i I h s :way .215 s dxall h select B Dive se gindi. with 6 27and28) rs called are returned as described .i b y the pi 'tiqularnatiii'e o th co thejcallingfcuu rent. 'nt calling subse 1 hook tl is reei ve r from the This sounds the rves t the linecalled i s-engagedntjt'hat tlie system described lic able to station s y'ithfifl il andmore sixbscrlb The ini berlof selectors employed has 'nierely to beincreased by a second "sel select tlie tt a first selectoi increasedcllidiilg ,e ali n o f.,: simulta he number q f' .prelimi a1 'ith 9"subscriber two caters I claim I 1. An utoma'tic teleplione selectingsystem ei'n flo ing'difler nt' 'nibinationsof no currentl sequentncrement of one or ZIDQIQJO ,"grooved menib e U l spending tov saidombinat ion is enabled te v I fall into :theugroov es onqthe ggr ooye xyem-i m w tongues remain criber is 1 11- i.

h l r beinotitied.

' that when the.

n circuit bridged s' a signal to;

w {arm areas-t brought axiall l initial positions ,1-(mi d, 1: U =1 g 3.selector for an.automatictelephoneuOS- selecting systemofthetypedescribed; com

, magnets, meansdoperated by said magnetsv .7

for nioying said disks in desired; combine-e; Y

tions, each combination being arranged to 115 7 bring only one semi thegr ooveson a,ll:the.

; disks axially in line contact carrying; nst a oppositethegroove-s whenbr0ught;a-x' ially of the grooved disks. 1

amt-s "and ieui'r e nt impulses for disa ,t; u \,.-u tingu sh ng thevarious subscribers comto the number of different ciphers usedtodistinguish thesubscribers, means for send ing current .thro i gh tliecontacts 0 id rows desired, selectorsilocated ataiigcsn tral station,magnets on saidfielectcrs, (lit-J ferent magnets oreombinationiof{inagnetg being energized when current is sent. throughthe contacts of different rows-,emovi able grooved members correspondingto said magnets and operable by the same, tongues placed yariously overthe grooved and nongrooved partslof said men'iber, said ltongues zu'a t09 Q$P ;t-Qfl fixe combination at impulses; so thaton tlieko currence ofsaid conlbina tiontandflthe; com-: I

ily th ngue:

bers \yhile the reinaini out of the grow-es. I a a t-, a 1

S QL o 1 autoniat selecting system of the type-describedcom prising aplurality oI d sksiiiionntedparallel to one, :Lliuilltlbfllld rotatable:

v r qghz alsosmall angle, notches on theiper1pheries-.-of;

Said dis s, said notches beingw axially in line and axiallydisplacedtothe notches ofjadjacent disks in a predetermined manner-,-

electro-niagnets means operated by saida'95 magnetsfor moving saiddiskssintdes ed con binationspeach. eonibination being a ranged tob'ring only one se t oiieigrhwu n al the disks, axially in'line Contactca the, grooy heninto said gro and means for U prisingva plurality ofdisks .mountedgparalle to one another and rotatable through a smallnangle, notches on the peripherieseof gaid disks, said notchesbeingiaxially inlineaanddlO aniall'y displaced to tlie notches ofadjacent;

disks" inaagpredetermined. inanneiz i'eleetro in line and adapted tofalliinto a e i n-line to effect-selection, a magnet adapted 12.0 todraw said armsagainsfithe peripherie disks, said notches being axiallyin -lin eaand axially displaced to thenotehes of adjacent,- disksin apredetermined manner -electr -LBO magnets, means operated by said manets for moving said disks in desired com inations, each combinationbeing arranged to bring only one set of the grooves on all the disksaxially in line, means for retaining the disks in the positions to whichthey are moved by the magnets.

5. In an automatic telephone enchango of the type described, preliminary:sel first selectors, means for automatically" con necting thepreliminary selectors tg a disenga of re ays operable from thepreliminary selector, multiple contact arms operated by said relays sothat when the firstfrelay is operated by the preliminary selector -itautomatically cuts out the first selector of the set of first selectorsand connects the next caller to the second relay of the set and secondselector of the set of first selectors and so on through the set.

6. In an automatic telephone system of the type described, a selector,means for sending combinations of current impulses to said selector,magnets in said selector adapted to be energized in combinationscorresponding to the combinations of current impulses sent, meansoperated by the diflerent combinations of energized magnets foreffecting selection, a switch arm at said selector, means for movingsaid switch arm stepwise once after each combination of impulses,

' and means for returning said switch arm when desired.

7. In an automatic telephone system of the type described, a selector,means for sending combinations of current impulses to said selector,magnets in said selector adapted to be energized in combinationscorresponding to the combinations of current impulses sent, meansoperated by the difierent combinations of energized magnets foreffecting selection, a switch arm at said selector, means for movingsaid switch arm stepwise once after each combination of impulses, meansfor returning said switch arm, when desired and means rendered operativeby said switch arm when returned for efiecting the return of theselecting means to their initial positions.

8. In an automatic telephone stem of the type described, sets of firstse ectors, prehminary selectors for selecting a disengaged firstselector of the desired set, means for copies at um patent my be mama edfirst selector, comprising a group,v

tem comprising the subscribers station for sending comsendingcombinations of current impulses to the first selector selected by thepreliminary selector, sets of second selectors for said first selectorsa relay (r rendered operative by'sending a combination of currentimpulses to the first selector, for establishing communication betweenvthe second selector and the first selector, and means in- .terposedbetween the first and second selectorffor connecting said first selectorto a disengaged member of the set of second selectors. 9. An automatictelephone selecting sysa sending device located at binations of currentimpulses, diflerent combinations being arranged to correspond todifierent digitsused for numbering the subscribers, magnets located atthe central station and arranged to be energized in differentcombinations corresponding to the combinations of impulses transmittedfrom the calling. station, controlling members moved by said magnetswhen energized, and means rendered operative only by the movement of aparticular combination of said controlling members for connecting onesubscriber to another.

' 10. An automatic telephone exchange system comprising a sender,located at the subscribers station, for sending nine differentcombinations of current impulses and comprising 9 rows of contactscorresponding one to each combination, magnets located at a centralstation and equal in number to the number of terms in the combinationsrequired for selection of any given subscriber, a number of movablemembers controlled one by each of said magnets and a plurality ofcontacts to be selected said contacts cooperating with the movablemembers in such a,!nanner that when a particular combination of themovable members is moved onl that one of said contacts is operated whichcorresponds to the combinations of current impulses which operated themovable memers.

In witness whereof I have hereunto set my hand in the prwence of twowitnesses.

' ERNSTBLOS. Witnesses:

Wowmun Ham-T, HENRY Hnsrnn.

Washington, D? 0; a

